A “technical issue” with a booking and reservation system used by several U.S. airlines caused delays and headaches at airports across the country Monday. “Earlier today, Sabre had a brief technical issue that impacted multiple carriers, including American. This technical issue has been resolved,” said American Airlines in an emailed statement. “We apologize to our customers for the inconvenience.” Travelers and would be customers took to social media Monday to report problems trying to book travel or check in for flights on American Airlines, JetBlue, Alaska Airlines and others. It’s unclear whether the issues have been resolved for all airlines. “Due to a Sabre issue impacting multiple airlines, JetBlue customers may experience issues with booking or check-in on jetblue.com, airport kiosks, or our mobile app,” JetBlue said in an emailed statement. “We are working to resolve the issue and apologize to our customers for the inconvenience.” Sabre and Alaska Airlines didn’t immediately respond to requests for comment. This article originally appeared on CNET.